Steve Jones

Encrypting Data in SQL ServerSteve Jones

Editor in ChiefSQLServerCentral, Red Gate Software

#sqlinthecity

Agenda• What is encryption?• Encryption in SQL Server• Communications• Transparent Data Encryption• Hashing• Keys• Symmetric Keys• Asymmetric Keys

• What is encryption?• Encryption in SQL Server• Communications• Transparent Data Encryption• Hashing• Keys• Symmetric Keys• Asymmetric Keys

Agenda

What is Encryption?

encryption is the process of transforming information (referred to as plaintext) using an algorithm (called a cipher) to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key. The result of the process is encrypted information (in cryptography, referred to as ciphertext).

- Wikipedia

Simple CiphersSimple Ciphers

ABCDEFGHIJKLMNOPQRSTUVWXYZ

DEFGHIJKLMNOPQRSTUVWXYZABC

WKLV LV HQFUBSWHG

Simple Ciphers

ABCDEFGHIJKLMNOPQRSTUVWXYZ

DEFGHIJKLMNOPQRSTUVWXYZABC

WKLV LV HQFUBSWHG

THIS IS ENCRYPTED

Complex Encryption

Results:-------------------------------------------0x00E2A26D824E22468392458DE6F450DA0100000025DE09E

F3AD8D7C989E393BF9FE1368D04C1B9BEE086EFFDF6F77AF9E3A3B8142F23723D536C72C216D6F9B104A5E44A

Encryption in SQL Server

Client

SQL Server Instance

Client file system

Communication Link(the wire)

SQL Server memory

SQL Server data filesBackup files

Client

SQL Server Instance

Client file system

SQL Server memory

Client

SQL Server Instance

Client file system

SL Server memorySQL Server memory

Client

SQL Server Instance

Client file system

SQL Server memory

Client

SQL Server Instance

Client file system

SQL Server memory

Client

SQL Server Instance

Client file system

SQL Server memory

Client

SQL Server Instance

Client file system

SQL Server memory

Encryption Hierarchy

Communications

• Encrypt the connection to/from SQL Server– Encrypt “the wire”

• Two options– SSL encryption from SQL Server– IPSec encryption at the Windows host

network layer.

SSL Communications

• Install certificate on SQL Server, set the FORCE ENCRYPTION options

– Yes = required– No = client option

• Certificate must be valid based on the system time

• DO NOT USE SELF SIGNED CERTIFICATES• All rules in BOL

– Encrypting Connections to SQL Server– How to: Enable Encrypted Connections to the Database

Engine

Transparent Data Encryption

• TDE introduced in SQL Server 2008• Protects the data at rest by encrypting the

data on disk.– The transaction log is encrypted– Backups are encrypted (can eliminate

compression)– Tempdb is encrypted for all operations.– Replication data is not encrypted– Filestream data is not encrypted

• Implemented with a simple ALTER DATABASE command

ALTER DATABASE AdventureWorks2008R2 SET ENCRYPTION ON; GO

• Encryption is handled by the Database Encryption Key (DEK)

• Requires a Database Master Key (DMK) and a Certificate to protect the DEK

• Backups of the certificate protecting the DEK are necessary to restore a backup.

DemoTransparent Data Encryption

• Overhead is < 5%• Enterprise Edition only (not BI edition)• Value?• Third Party Tools

Hashing

• “A hash function is any algorithm or subroutine that maps large data sets, called keys, to smaller data sets.” - Wikipedia

Hashing

• SQL Server uses the HASHBYTES functions• CHECKSUM() or BINARY_CHECKSUM() can

also be used.• other implementations using .NET/CLR are

better. (see Expert SQL Server Encryption, Michael Coles)

• SQL Server 2012 adds SHA2_256 and SHA2_512 algorithms.

Hashing

Hashing or Encryption

• Hashing is not really encryption– Decryption is not supported (usually)

• Hashing is deterministic, encryption is not• Hashing is quicker• In general, a hash of searchable data can be

used to allow indexing of encrypted data.– Caveat – Only hash the portion of the encrypted

data needed for searching, e.g. last four digits of a credit card number.

• Choose the strongest algorithm available in your version.– SQL Server 2008 – SHA1– SQL Server 2012 - SHA2_512

• Multiple Keys in SQL Server– Service Master Key– Database Master Key– Database Encryption Key– Symmetric Keys– Asymmetric Keys– Certificates

The Encryption Hierarchy

Service Master Key

• Service Master Key = SMK• The Service Master Key is created

when it is first needed. No CREATE DDL

• Secured by Windows DPAPI (default)• Accessed by Service Account for

database engine, or a principal with access to the service account name and password

Service Master Key

• Must be manually backed up. BACKUP SERVICE MASTER KEY

• Must be restored in a DR situation to open other keys secured by this key (Database Master Keys)

• Can be regenerated if necessary.– This can cause data loss

• Encryption is now AES

Database Master Key

• Database Master Key = DMK• The Database Master Key is created by

an administrator (CREATE/ALTER DDL)• This is secured by the SMK and a

password (TripleDES encryption in 2008, AES in 2012)

• This can be secured by password only (DROP ENCRYPTION BY SERVICE MASTER KEY option)

Database Master Key

• Backup and restore using DDL commands

BACKUP MASTER KEY RESTORE MASTER KEY

• OPEN/CLOSE manually if not protected by the SMK

• Attach/restore of an encrypted database requires the password for the DMK

• You can alter the DMK to add SMK encryption after attach/restore

Symmetric Encryption

• Like a normal key lock• The key that encrypts the data also

decrypts the data

Symmetric Keys

• Symmetric Keys are created in a database and are always in that database (cannot be backed up/restored)

• Symmetric Keys are deterministic, and can be duplicated with the same creation parameters.

• Symmetric keys require less resources than asymmetric keys, but there is still an additional CPU load from their use.

Symmetric Keys

• The identity value always generates the same GUID for the key. These must be unique in a session.

• The KEY_SOURCE and IDENTITY can be used to recreate a key. If you choose the same ones, and the same algorithm, you’ll get the same key

• You can, and should, secure these keys with asymmetric keys

Symmetric Keys

• The algorithm used is stored in the header of the encrypted data.

• You can generate temporary keys for encryption/decryption

• CREATE SYMMETRIC KEY #MyTempKey • Encryption with passphrases uses symmetric keys (TripleDES)

Asymmetric Encryption

• Asymmetric keys are unlike keys and locks in the real world.

• Based on factoring very large prime numbers.

• More secure than symmetric keys• Require more resources for

encryption/decryption than symmetric keys

Now is the time for all good men to come to

the aid of their countryAsymmetric Algorithm

0x26CD66B61E50369CBBDB42F484237370E02238EEAE588E06D00F8D0C6FAB5C48F68639ABB4003564CFB48A41BA373CFA411E99D3AB31A1B7CE40

Asymmetric Algorithm

0xE7A518047A8D3836B76006D9CE04DA2F803607A57CD7F9EE855FC3451EB02A076F28DD614BA841AC756E52CFEC4006746480C8204D579083C4AD0D627

Key 10x26CD66B61E50369CBBDB42F484237370E02238EEAE588E06D00F8D0C6FAB5C48F68639ABB4003564CFB48A41BA373CFA411E99D3AB31A1B7CE

40CB35

0x26CD66B61E50369CBBDB42F484237370E02238EEAE588E06D00F8D0C6FAB5C48F68639ABB4003564CFB48A41BA373CFA411E99D3AB31A1B7CE

40CB35

the aid of their country

Key 1 – Private Key

Key 2 – Public Key

Keys 1 and 2 are paired and generated together.

One is referred to as a private key and the other a public key. Only the user has the private key, but the public key is distributed to everyone

Anyone encrypts with Steve’s Public Key 0x26CD66B61E50369

CBBDB42F484237370E02238EEAE588E06D00F8D0C6FAB5C48F68639ABB4003564CFB48A41BA373CFA411E99D3AB31A1B7CE40

Only Steve can decrypt with his private key

Steve can encrypt with his private key 0x26CD66B61E50369

CBBDB42F484237370E02238EEAE588E06D00F8D0C6FAB5C48F68639ABB4003564CFB48A41BA373CFA411E99D3AB31A1B7CE40

Anyone can decrypt with Steve’s public key

Now is the time

Steve can encrypt with his private key

0x26CD66B61E50369CBBDB42F48423737

Steve encrypts again with Andy’s Public Key

0x48385D8A87BD329FF328E476BC234

0x26CD66B61E50369CBBDB42F48423737

0x48385D8A87BD329FF328E476

Andy decrypts the outer message with his private key

0x26CD66B61E50369CBBDB42F48423737

Andy then decrypts with Steve’s Public key to verify the message is from Steve

Now is the time0x26CD66B61E50369CBBDB42F48423737

• Use DDL to create asymmetric keys (CREATE/DROP/ALTER)

• Can be created outside the server (FROM FILE option)– SN.exe (Visual Studio SDK)– Makecert (Windows SDK)

• You can encrypt an asymmetric key with a password. – This will be required for decryption– Not required for encryption

• Asymmetric keys are usually used to encrypt symmetric keys, which encrypt the data. This balances security with resources

• You can remove the private key (prevents decryption in that db).

Certificates

• Certificates are asymmetric keys with additional metadata.

• Expiration dates are not enforced by SQL Server– Administrators must decrypt/re-encrypt the

data and remove the old certificates– Useful for marking the key rotation dates

(query sys.certificates)• To restore certificates, use CREATE CERTIFICATE.• SQL Server 2012 increases the maximum

certificate length to 4,096.• Always use the longest length you can.

Key Length

• Use long keys• Use strong algorithms (MD5/SHA1 = bad)• DKIM attack on Google’s mail system*

– 384 bit key cracked on high end laptop– 512 bit key cracked for ~$75 using AWS– 768 bit key could be cracked by large

orgs– This changes all the time

www.wired.com/threatlevel/2012/10/dkim-vulnerability-widespread/all/

The End

• Questions?• Don’t forget to fill out your feedback forms• Resources at the end of the PPT• www.sqlservercentral.com/forums• www.voiceofthedba.com/talks

References

• Encryption - http://en.wikipedia.org/wiki/Encryption• Understanding TDE - http://msdn.microsoft.com/en-us/library/bb934049.aspx• Hash Function - http://en.wikipedia.org/wiki/Hash_function• Rainbow Tables - http://en.wikipedia.org/wiki/Rainbow_table• Transparent Data Encryption –

https://www.simple-talk.com/sql/database-administration/transparent-data-encryption/• How to enable/remove Transparent Data Encryption (TDE) -

http://blogs.msdn.com/b/batuhanyildiz/archive/2012/10/16/how-to-enable-remove-transparent-data-encryption-tde.aspx

• Sys.database_encryption_keys - http://msdn.microsoft.com/en-us/library/bb677274.aspx• TDE and Backup Compression -

http://sqlcat.com/sqlcat/b/technicalnotes/archive/2009/02/16/tuning-backup-compression-part-2.aspx

• Encrypting Connections to SQL Server - http://msdn.microsoft.com/en-us/library/ms189067.aspx

• ENCRYPTBYCERT - http://technet.microsoft.com/en-us/library/ms188061.aspx• DECRYPTBYKEY - http://technet.microsoft.com/en-us/library/ms181860.aspx• DECRYPTBYASYMKEY - http://technet.microsoft.com/en-us/library/ms189507.aspx• DECRYPTBYCERT - http://technet.microsoft.com/en-us/library/ms178601.aspx• DECRYPTBYKEYAUTOASYMKEY - http://technet.microsoft.com/en-us/library/ms365420.aspx• DECRYPTBYKEYAUTOCERT - http://technet.microsoft.com/en-us/library/ms182559.aspx

References

• HASHBYTES - http://msdn.microsoft.com/en-us/library/ms174415.aspx• CHECKSUM() - http://msdn.microsoft.com/en-us/library/ms189788.aspx• BINARY_CHECKSUM() - http://msdn.microsoft.com/en-us/library/ms173784.aspx• Expert SQL Server Encryption - http://www.amazon.com/gp/product/1430224649?

ie=UTF8&tag=redgatsof-20&linkCode=as2&camp=1789&creative=9325&creativeASIN=1430224649

• Data Hashing in SQL Server - http://blogs.msdn.com/b/sqlsecurity/archive/2011/08/26/data-hashing.aspx

• CREATE ASYMMETRIC KEY - http://technet.microsoft.com/en-us/library/ms174430.aspx• ALTER ASYMMETRIC KEY - http://technet.microsoft.com/en-us/library/ms187311.aspx• CREATE CERTIFICATE - http://technet.microsoft.com/en-us/library/ms187798.aspx• ALTER CERTIFICATE - http://technet.microsoft.com/en-us/library/ms189511.aspx• BACKUP CERTIFICATE - http://technet.microsoft.com/en-us/library/ms178578.aspx• sys.certificates - http://technet.microsoft.com/en-us/library/ms189774.aspx• ENCRYPTBYPASSPHRASE - http://technet.microsoft.com/en-us/library/ms188910.aspx• ENCRYPTBYKEY - http://technet.microsoft.com/en-us/library/ms174361.aspx• ENCRYPTBYASYMKEY - http://technet.microsoft.com/en-us/library/ms186950.aspx

References

• http://blogs.msdn.com/b/raulga/archive/2006/03/11/549754.aspx• Windows SDK (Makecert) -

http://msdn.microsoft.com/en-us/windowsserver/bb980924.aspx• SN.EXE - http://msdn.microsoft.com/en-us/library/k5b5tt23.aspx• Subway Hacked - http://arstechnica.com/business/news/2011/12/how-

hackers-gave-subway-a-30-million-lesson-in-point-of-sale-security.ars• Install SSL Certificate -

http://blogs.msdn.com/b/jorgepc/archive/2008/02/19/enabling-certificates-for-ssl-connection-on-sql-server-2005-clustered-installation.aspx

• Encrypting Connections to SQL Server - http://msdn.microsoft.com/en-us/library/ms189067.aspx

• SQL Server 2005: A look at the master keys - part 2 - http://blogs.msdn.com/b/lcris/archive/2005/09/30/475822.aspx

• Cryptography in SQL Server http://msdn.microsoft.com/en-us/library/cc837966%28v=sql.100%29.aspx

• http://arstechnica.com/security/2013/05/how-crackers-make-minced-meat-out-of-your-passwords/

Images

• Enigma Machine - http://www.flickr.com/photos/badwsky/34164244/• The Encryption Hierarchy from BOL -

http://msdn.microsoft.com/en-US/library/ms189586%28v=SQL.90%29.aspx• Hashing Image -

http://upload.wikimedia.org/wikipedia/commons/thumb/5/58/Hash_table_4_1_1_0_0_1_0_LL.svg/240px-Hash_table_4_1_1_0_0_1_0_LL.svg.png

• TDE Structure - http://msdn.microsoft.com/en-us/library/bb934049.aspx

Steve Jones - Encrypting Data

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